(a) Field of the Invention
The present invention relates to curtain blinds, and more particularly to a curtain blind take-up drive mechanism with non-slip effect, providing freehand turn operation. The non-slip effect is further configured to prevent slats of the blind from slipping down under their own weight.
(b) Description of the Prior Art
Referring to FIG. 1, which shows a schematic view of a Venetian blind, including a head rail 1 lengthwise configured with a drive shaft 14 therein. A reel 15 is respectively attached to both right and left ends of the drive shaft 14. A power end is actuated through any transmission of a turntable drive unit 12. Indirect operation of a lift cord 130 actuates the reels 15, and thereof reel cords 16 are enabled to take-up or let-down slats 11. Upon a plurality of the salts 11 of a prior Venetian blind coming together, the slats 11 thereupon form a specific synergistic weight with proportional downward gravitational pull. The gravitational pull accordingly pulls on the reels 15 via the reel cords 16 causing the drive shaft 14 to reversibly rotate thereof, and the turntable drive unit 12 correspondingly begins idle running. Consequently the slats 11 slip down and open up.
In order to counteract the aforementioned shortcomings, a conventional blind includes related positioning of components of the turntable drive unit 12, and is additionally configured with resilient tensile components, and therewith utilizing a great variety of designs to achieve a non-slip stoppage component effect, such as resilience or unilaterality of a ratchet to clasp components, whereby a stoppage mechanism is formed. However, the aforesaid non-slip mechanisms are ineffective, for instance, resilience under certain conditions or undulations of indeterminate external forces will likewise cause the slats to slip downwards. Moreover, design of a unilateral ratchet clasp requires a frictional force to actuate a holding mechanism, and because cut-in angles or disparate strength of frictional forces, the frictional force often results in an idling situation arising. Recently, electric motor control has been employed, as well as utilizing electromagnetically controlled electromagnetic clutch methods to achieve a non-slip effect for a take-up and let-down locking control.
The aforementioned non-slip mechanisms are especially suitable when applied to large-scale level slat style curtain units. More importantly, when wind power blows the blind slats, force of traction is produced, and dragging down of the slats results thereof. Furthermore, based on prior art design, whereby a lift cord 130 is employed to operate the take-up and let-down of the blind, the lift cord 130 is designed as a closed loop, whereby a lower section of the loop is a closed end, thereby forming a closed loop. The closed loop of the lift cord 130 can be dangerous to children, whereby when children are playing close to the lift cord 130, the lift cord 130 can wind round the children's limbs and entangles the children thereof.